Numerator and denominator
The numerator is the top part of the fraction, while the denominator is the bottom part of the fraction.
NUmerator = Up (U for up)
Denominator = Down (D for Down)
The denominator is dominated by the number on the top.
Here 3 is the numerator and 4 is the denominator.
Here 17 is the numerator and 6 is the denominator.